This invention relates to a fixture for locking a pipe fitting to a rotatable welding table so that a socket weld can be formed in one continuous operation without removing the fitting from the fixture.
Many pipe fittings in use today are provided with sockets that are capable of receiving a pipe section therein. The weld is usually closed by running a bead about the joint region between the pipe and the fitting. This type of weld is generally referred to as a socket weld. One of the difficulties encountered by steam fitters when attempting to form a socket weld is the inability of the welder to run a bead about the circular joint region in one continuous operation. Breaking the bead before completion of the weld can create a number of problems. Attempting to pick up the bead after it has been broken requires a good deal of skill on the part of the welder. If the operation is improperly carried out, the integrity of the weld can be adversely effected. Furthermore striking the arc a number of times along the path of the bead produces unwanted sputtering of the weld material outside the weld area. Having to make and break the bead a number of times extends the time needed to complete the operation thereby lowering the productivity of the worker while, at the same time, raising the cost of fabrication.
Many pipe fittings today are arc welded in the field upon relatively large stationary tables or work benches which do not permit the welder to move freely about the work. The many lines servicing the equipment also severely limit, the welders mobility and, as a consequence, the work sometimes must be repositioned one or more times before a typical socket weld is completed. Pipe fittings requiring socket welds are generally secured to the table using C-clamps or other vice-like holding fixtures having coacting jaws that are designed to close over the work. A portion of the weld joint region is thus usually shielded from the welding rod by the jaws again necessitating repositioning of the work a number of times before the weld can be completed. As noted, interruption of the weld and repositioning of the work wastes a good deal of valuable time and can under certain conditions adversely effect the integrity of the weld.
Devices showing the use of clamps or vice jaws to secure pipes or pipe fittings in holding fixtures are shown in the U.S. Pat. Nos. 2,883,184; 3,971,552; and 4,363,475. A pipe fitting stand having an adjustable cradle for supporting a typical sanitary drain is shown in U.S. Pat. No. 2,853,771. Similarly, a fixture for holding a piston rod pin while it is being inserted into a rod is described in U.S. Pat. No. 2,070,380. These devices, however, do not lend themselves for use in securing pipe fixtures to a welding bench because, in all cases, the jaws of the fixture close over a good portion of the work piece and thus shield at least a portion of the weld area from this welding rod.